I already fine tuned the lens, value needed was only -1. The sides are sharp, just the most extreme corners show a little bit of blur. Of course, it's hard to discern if it's an effect of DOF, didn't do any "brick wall" tests yet.

Can't test it right now as I sent it in to Nikon today for checking why my copy emits a high-pitched whine when focusing. We checked against other Nikkor lenses at the shop, all were completely silent.